There are two methods for storage of oocytes: slow freezing or vitrification. Slow freezing is the conventional method and has been successfully used for embryos since 1983 and more recently for oocytes. Recent reports indicate that vitrification may be more successful than slow freezing. However, the technique has not been rigorously validated to date. The aim of this study is to determine the rate of cryosurvival of mature oocytes following vitrification, and to then compare the reproductive potential of vitrified oocytes relative to those which have not been cryopreserved.